Process of producing self-crimping fibers



June 1955 s. w. SPANGLER 3,188,714

PROCESS OF PRODUCING SELF-CRIMPING FIBERS Filed March 22, 1963 C [J O #07- AIR 6. 7 INVENTOR.

FIG. 1. BY

GORDON W. SPANGLER 3,188,714 PROCESS OF PRODUC NG SELF-CRIMPING FIBERS (Gordon W. Spangler, Kingsport, Tenn, assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Mar. 22, 1963, Ser. No. 267,268 Claims. (CI. 28-72) This invention relates to self-crimping synthetic textile fibers and more particularly to a process of producing such fibers from linear high molecular weight fiber forming polymers such as polyesters in such manner as to produce therein a three-dimensional, random or nonuniform crimp.

It is known that crimped filaments can be prepared from thermoplastic polymers by the melt spinning process in which the filaments as they emerge in a molten condition from a spinnerette are subjected, in close proximity to the spinnerette, to the action of a quenching medium, such as a jet of air which is initially directed to one side Y only of the filaments and thereafter drafting the filaments and releasing tension thereon. Crimping apparently results from the stresses set up in the polymeric material by the localized action of the quenching medium on one side of the filaments. For example, in the patent to Lees, 3,061,874, itvis stated that it has been previously recognized that crimped filaments can be prepared from certain thermoplastic polymers by extruding the molten polymers-in the form of filaments, quenching the extruded filaments in an asymmetric manner so that one side of each filament is solidified before the other side, and orienting the extruded filaments. Asymmetric cooling of a filament is achieved by employing as the quenching medium a jet of air or other gas directed upon one side of the exwhich the same essential method of asymmetric quenching, that is quenching the molten filaments on one side only, is accomplished in such manner as to produce fibers of specified physical properties as defined in the patent. It is apparent from these disclosures that the crimp obtained by the means disclosed, while three dimensional, is not a true random or nonuniform crimp, but is in the nature of a helical or corkscrew crimp due to the fact that after drafting the filaments and relaxing the tension thereon they tend to curl up in the form of a helix the turns or convolutions of which are more or less uniform along the filament length.

As will be more fully set forth hereinafter, the present invention is a specific process of obtaining a three dimensional, completely random or nonuniform crimp in preformed polymeric filaments or fibers by drafting the filamentary material in a cold liquid which results in the production in the fiber mass of built-in stresses which, upon release of tension from, and application of heat to, the fibers will produce the desired crimping effect but does not, as in the above-mentioned prior art disclosures, involve any special quenching technique nor result in helical conformation of the individual filaments.

This invention accordingly has as an object the production from various linear high molecular weight fiber forming polymeric materials of a self-crimping textile fiber in which the crimp is of a three dimensional, random or nonuniform conformation.

Qii

A further object is to provide a process of producing from linear high molecular weight fiber forming polymeric materials a textile fiber which, upon being subjected to drafting followed by release of tension, will be self-crimping and will assume a three dimensional, truly random or nonuniform crimp.

A still further object is to provide a process of producing a self-crimping synthetic textile fiber from a linear high molecular weight fiber forming polymeric material by drafting the fiber under such conditions that upon releasing tension and applying heat the fiber will assume a three dimensional, truly random or nonuniform crimp.

A specific object is to provide as a new product an improved self-crimping textile fiber from a linear high molecular weight polyester material which will have a three dimensional, truly random or nonuniform crimp.

Other objects will appear hereinafter.

These objects are accomplished by the following invention which in its broader aspects, comprises subjecting preformed filaments composed of a linear high molecular weight fiber forming polymer such as a polyester exemplified by polyethylene terephthalate or poly(1,4--

cyclohexylencdimethyleneterephthalate), which filaments have been quenched but not drafted, to drafting in a fluid bath composed of a liquid which is non-solvent with respect to the polyester material, such as a water bath maintained at a temperature below the critical draft temperature of the synthetic polymeric material, and after removal of the filaments from the drafting bath, releasing the tension thereon and subjecting them to a heat treating step in which the filaments are free to relax and shrink. Under these conditions the filaments become self-crimping in a three dimensional, truly random or nonuniform manner.

Reference has been made to the critical drafting temperature. By this is meant the maximum temperature through which a thermoplastic fiber forming material can be drafted to produce fibers that curl up or crimp in a truly random or nonuniform three dimensional manner upon release of tension from the filamentary material after drafting and during a subsequent heat treating or heat setting step. This temperature is dependent upon the physical and chemical characteristics of the particular fiber forming materials undergoing processing and will vary from one polymeric material to another. When a fiber is drafted above this critical draft temperature. self-crimping characteristics are not developed in the fiber material and it remains straight and uncrimped during the heat setting step as will be more fully described hereinafter and illustrated by reference to the drawing forming a part of this specification. Thus it will be seen that each different fiber forming material has its own characteristic critical draft temperature. In the case of polyethylene terephthalate, for example, the critical draft temperature will be about 25 C. and in accordance with the present invention self-crimping fibers composed of this material can be produced by drafting in a water bath or similar inert liquid at a temperature within the range of 1 C. to 25 C., and preferably within the range of 1 C. to 10 C. In the case of polyesters derived from l,4-cyclohexanedimethanol, as for example, poly(1,4 cyclohexylenedimethyleneterephthalate) the critical draft temperature will be about C. and a satisfactory drafting temperature range will be from about 50 C. to about 80 C. and preferably within the,

exothermic process, that is, heat is given off during orientation. When such a filament is drafted in a cold liquid medium such as water heat is removed more rapidly from the outside of the filaments than from the inside thus creating a temperature differential from outside to inside of the filament. Since the filament is normally drafted at a constant ratio the cold outside of the filament requires more force to accomplish drafting than does the warm and more fluid inside material. Following drafting and relaxation of tension on the filament this difference in internal and external draft tension causes the outside of the filament to relax or shrink to a greater degree than does the inside. Thus the filaments tend to shrink up irregularly or crimp when heat is applied thereto in the customary heat setting or preshrinking step. Since there will be differential and randomly disposed stresses present in the body of the filamentary material from inside to outside it follows that the crimping, wrinkling or shrinking up of the filamentary material will also take place in a three dimensional or truly random or nonuniform manner as distinguished from simply curling up in a spiral conformation.

While not limited thereto the present invention finds particular application to the production of self-crimping filaments and fibers from high molecular weight linear fiber forming polyesters typified by polyethylene terephth'alate and poly(l,4cyc1ohexylenedimethyleneterephthalate). These fiber forming materials may be produced in accordance with known procedures. For examples, polyethylene terephth'alate may be produced in accordance with the disclosure of US. patent to Whinfield and Dickson 2,465,319 andpolyesters of thetype of poly( 1,4- cyclohexylenedimethyleneterephthalate) may be produced in accordance with the disclosure of US. patent to Kibler, Bell and Smith, 3,033,822.

Filaments produced from the above-described polyester materials may be produced by the well-known melt spinning process the details of which are well known to those skilled in the art to which the invention relates. It will be noted, however, that the process of my invention involves applying the steps of the process to a preformed filamentary material which maybe in the forms of filamen ts which have just been produced by the melt spinning process or to filaments which have been previously melt spun, wound up on a package and then led through the drafting and heat treating steps.

In the following examples and description I have set forth several of the preferred embodiments of my invention but they are included merely for purposes of illustration and not as a limitation thereof.

' My invention will be more readily understood by reference to the severa'. figures of the drawing in which,

FIGURE 1 is a seruidiagrammatic illustration in the form of a flow sheet illustrating one method by which a strand of preformed linear high molecular weight polymeric material, such as a polyester after extrusionvand que ching, is treated in accordance with the invention.

FIGURE 2 is an illustration of a self-crimping synthetic textile fiber product produced in accordance with the invention and illustrating the three dimensional, truly random or nonuniform crimp obtained therein.

FIGURE 3 is an illustration of the same polymeric fiber material of FIGURE 2 which has been produced by the process illustrated in FIGURE 1 but drafted at a temperature above its critical draft temperature and, as a result of the higher drafting tempera-ture, contains no appreciable degree of crimp.

Referring to FIGURE 1 of the drawing, the numeral 1 designates a strand of preformed filaments, as for example, a strand of filaments composed of polyethylene terephthalate or poly(1,4 cyclohexylenedimethyleneterephthalate) which comes directly from a melt spinning operation or may be supplied to the operation from a package upon which the filaments have been previously wound. The strand of filaments 1 then pass over a set of feed rolls 2 and 3 from which the strand is fed at a constant linear speed to a bath of cold liquid 4 maintained at a temperature below the critical draft temperature of the filamentary material undergoing treatment and contained in receptacle 5, the strand being lead over snubbing pins 6 and 7, thence to draft rolls 8 and 9. Draft roll 8 may be partially or wholly submerged in the cooling liquid to prevent the filaments, upon emerging from the bath, from being subject to any draft due to the softening effect thereon of the relatively warmer temperature of the air into which it emerges after leaving the cooling liquid.

The strand of filaments 1 passes from drafting rolls 8 and 9 to pinch rolls 10 and 11 which serve as squeeze rolls to remove excess water from the filamentary material and also to relieve the tension on the yarn so that it may be fed in a relaxed condition to the endless perforated metal conveyor belt 12 which is moved in the direction indicated by the arrow by passing over rolls 13 and 14 driven at an appropriate constant speed by means not shown. From the conveyor belt the filamentary material is conveyed to any desired collecting means for further treatment such as cutting into staple lengths, bailing, or any other desired operation.

Rolls 2 and 3 are operated at a constant speed and.

serve to feed the strand" of filamentary material into bath 4 at a constant rate. Draft rolls 8 and 9 are operated at a uniform linear speed which is two or more times greater than the linear speed of feed rolls 2 and 3 thus producing a draft on the yarn while it is in bath 4. Substantially all the tension on the yarn is confined to the bath between snubbing pins 6 and 7 and feed rolls 8 and 9 although some slight tension is produced while the yarn is being conveyed between rolls 2 and 3 to the snubbing pins.

Pinch rolls 10 and 11 are operated at substantially the same linear speed as draft rolls 8 and 9 and function to feed the yarn under substantially no tension to perforated conveyor belt 12. During the passage of the filamentary material through the cooling bath 4 heat is removed therefrom during this drafting or orienting step. Uponreaching the conveyor belt the yarn is in a completely relaxed condition and while being carried forward by belt 12 is subjected to the action of a draft of heated air or other inert gaseous medium maintained at a temperature which will always be suflicient to produce stability against shrinkageof the filaments in boiling water but yet low enough to preclude softening and sticking together of the filamentary material. Such a temperature is appropriately within the range of C. to 225 C. for most polyester material. The hot air or other inert heating medium passes through the conveyor belt and is supplied thereto from theund erside in the direction indicated by the arrows and also passes through the strand 1 of filamentary material and is finally withdrawn therefrom by means of the hood 15 and conduit 16 by suction means not shown. The belt is of suflicient width and length as easily to accommodate the number of filaments which are disposed thereon. Distribution of the filaments on the belt may be by any appropriate means such as by an oscillating festooning device or any other similar mechanism which will evenly deposit and distribute the material. The linear speed of the belt is so controlled as to permit the filamentary material being conveyed thereby to become uniformly heated ina relaxed condition. In general the material may remain on the belt for a period of 3 to 15 minutes although 5 minutes is generally sufficient when employing a temperature of 125 C. to 225 C. During the heat setting or shrinkage stabilizing step the filamentary material is maintained in' a completely relaxed state and the random internal stresses produced therein during the drafting step are relaxed in a random manner with the result that the yarn undergoes a three dimensional truly random or nonuniform crimp.

If desired the filament strand 1, before being subje-cted to the heat setting step on the conveyor belt may first be cut into staple; of any desired length and the staples thereafter distributed on the moving belt where they are subjected to heating in a relaxed condition in the same manner as if they had been in filamentary form. The effect of heating the staple material will be the same as that produced in the filamentary material, that is, the fibers in a completely relaxed state will each acquire the three dimensional truly random or nonuniform crimped form as result of the release of the randomly distributed stresses in the material.

The invention will be more fully understood by reference to the following examples.

Example I Polyethylene terephthalate polymer having an intrinsic viscosity of 0.65 as measured in a solution of 40 percent tetrachloroethane and 60 percent phenol was spun from a spinnerette containing 200'holes 0.5 mm. in diameter at a rate of 30 lb./hr. and a temperature of 285 C. The yarn was wound up at .a rate of 1000 meters per minute and had a denier of 2000. The yarn intrinsic viscosity was 0.50. This yarn was drafted in .water at 3 C. at a ratio of 3.9:1 and an output speed of 30 meters per minute. After drafting, the yarn was heatset for five minutes at 150 C. The yarn shrank 30 percent when heatset and had a fine irregular three-dimensional crimp as shown in FIGURE 2. This yarn had a denier per filament of 4.2, a tenacity of 2 grams per denier, and an elongation of 80 percent.

Example II The same yarn as described in Example I was drafted at a ratio of 4.8 in water at 30 C. When this yarn was heatset 5 minutes at 150 C., the shrinkage was only 20 percent and the yarn was not crimped, the individual filaments still being straight as shown in FIGURE 3. The yarn had a denier per filament of 3, a tenacity of 3.7 grams per denier, and an elongation of 40 percent.

Example III Polyethylene terephthalate polymer having an intrinsic viscosity of 0.65 was spun from a 200 hole spinnerette (0.5 mm. diameter holes) at a rate of 26 lb./hr. and a melt temperature of 285 C. The yarn was wound up on a package at a rate of 700 meters per minute and had a denier of 2500. The yarn intrinsic viscosity was 0.60. This yarn was drafted in water at 3 C. at a ratio of 4:1 and an output draft speed of 30 meters per minute. When heatset at 150 C. for 5 minutes, the yarn shrunk 40 percent and produced an irregular, three dimensional crimp, each filament being crimped in a manner comparable to that of the material illustrated by FIGURE 2. The yard had a denier per filament of 4.8, a'tenacity of 1.7 grams per denier, and an elongation of 74 percent.

' Example IV Polyethylene terephthalate having an I.V. of 0.65 and containing 0.25 percent titanium dioxide was spun from a spinnerette containing 400 holes 0.4 mm. in diameter. The spinning temperature was 300 C., the yarn takeup rate was 1000 mm., the undrafted yarn denier was 1960, and the final yarn I.V. was 0.56. This yarn was drafted at 3.3:1 in water at 8 C. When heatset 5 minutes at 150 C., the yarn shrunk 55 percent and become crimped in the same manner as the yarns in Example III. This heatset yarn had a denier per filament of 2.4, a tenacity of 1.5 grams per denier, and an elongation of 97 percent.

6 Example VI The undrafted yarn as described in Example V was drafted 4.2:1 in water at 30 C. When heatset at 150 C. for 5 minutes, this yarn shrunk 25 percent and did not crimp.

Example VII Poly( 1 ,4-cyclohexylenedimethyleneterephthalate) polyester having an intrinsic viscosity of 0.80 was spun from a spinnerette having 150 holes 0.65 mm. in diameter at a rate of 20 lbs/hr. The yarn was spun with a spinning temperature of 305 C., a wind-up rate of 308 meters per minute, and an undrafted denier of 4500. The undrawn yarn I.V. was 0.61. This yarn was drafted at a ratio of 3.6:1 in a water bath at 70 C. at an output speed of 27 meters per minute. When heatset 5 minutes at 150 C., the yarn shrunk 50 percent and the filaments curled up to produce an irregular three dimensional crimp such as shown in FIGURE 2. The heatset yarn had a denier per filament of 16, a tenacity of 1.1 grams per denier, and an elongation of 91 percent.

Example VIII The undrafted yarn described in Example VII was drafted in water at C. at a ratio of 4.0: 1. This yarn when heatset 5 minutes at 150 C. shrunk 13 percent and did not curl up or crimp as was the case with the yarn illustrated in FIGURE 3. The heatset yarn had a denier per filament of 9, a tenacity of 2.6 grams per denier, and an elongation of 26 percent.

In certain of the above examples reference has been made to I.V. This refers to inherent viscosity which is a measure of the degree of polymerization of a polymeric compound and is calculated from the equation:-

where r is the ratio of the viscosity at 25 C. of a dilute (approximately .25 percent by weight) solution of the polymer in a solvent composed of 60 percent by weight of phenol and 40 percent by weight of tetrachloroethane to the viscosity of the solvent itself, and C is the concentration of the polymer in grams per cubic centimeters of the solution.

It will thus be seen from the above description and examples that by the present invention a simple economical and effective process has been provided for obtaining self-crimping fibers having a three dimensional truly random or nonuniform crimp. The process is thus to be distinguished from the prior art process of producing asymmetrically crimped filaments from synthetically linear polymeric materials such as polyesters by the fact that the process does not involve any special quenching technique nor does it result in a helical conformation of the individual filaments as distinguished from a three dimensional truly random or nonuniform crimp.

The crimped fibers of the invention find many uses typical among which may be mentioned its use as filling materials for pillows, the formation of bats useful for various purposes and may also be employed in staple form for the manufacture of spun yarn either alone or in admixture with other textile fibers such as those composed of cellulose acetate, viscose, acrylic fibers, cotton,-

wool, and other nature materials and synthetic fibers.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

I claim:

1. The process of producing a synthetic textile fiber having a three-dimensional, random crimp which com prises drafting a pre-spun, unoriented fiber composed of a linear, high molecular weight polyester fiber-forming 7 polymer in a liquid which is a nonsolvent for the polymer and maintained at a temperature below the critical draft temperature of the polymer and thereafter heating the fiber in the absence of tension, whereby built-in stresses, resulting from the drafting of the polymeric material in said liquid are released and three-dimensional, random crimping of the fiber occurs.

2. The process of producing a synthetic textile fiber having a three-dimensional, random crimp which comprises drafting a pre-spun, unoriented fiber composed of polyethylene terephthalate in a liquid which is a nonsolvent for polyethylene terephthalate and maintained at a temperature of 1-25 C. and thereafter heating the fiber in the absence of tension, whereby built-in stresses resulting from the drafting of the polymeric material in said liquid are released and three-dimensional, random crimping of the fiber occurs.

3. The process of producing a synthetic textile fiber having a three-dimensional random crimp which'comprises drafting a pre-spun, unoriented fiber composed of polyethylene terephthalate in a water bath maintained at a temperature of 1-25" C. and thereafter heating the fiber in the absence of tension to a temperature within the range of 125-225 C., whereby built-in stresses resulting from the drafting of the polymeric material in said water bath are released and three-dimensional, random crimping of the fiber occurs.

4. The process of producing a synthetic textile fiber having a three-dimensional, random crimp which comprises drafting a pre-spun, unoriented fiber composed of poly(1,4-cyclohexylenedirnethyleneterephthalate) in a liqprises drafting a pre-spun, unoriented fiber composed of poly(l,4-cyclohexylenedimethyleneterephthalate) in a water bath maintained at a temperature of -80 C. and thereafter heating the fiber in the absence of tension to a temperature within the range of HS-225 0., whereby built-in stresses resulting from the drafting of the polymeric material in said water bath are released and threedimensional, random crimping of the fiber occurs.

References Cited by the Examiner UNITED STATES PATENTS 2,369,395 2/45 Heymann 57-140 2,543,027 2/51 Jones 264 -168 2,604,689 7/52 Hebeler 264-168 2,917,805 12/59 Rokosz 28-72 2,974,391 3/61 Speakrnan et a1. 28-1- 3,019,507 2/ 62 Maragliano er a1. 2872 DONALD w. PARKER, Primary Examiner. RUSSELL C. MADER, MERVIN STEIN, Examiners. 

1. THE PROCESS OF PRODUCING A SYNTHETIC TEXTILE FIBER HAVING A THREE-DIMENSIONAL, RANDOM CRIMP WHICH COMPRISES DRAFTING A PRE-SPUN, UNORIENTED FIBER COMPOSED OF A LINEAR, HIGH MOLECULAR WEIGHT POLYESTER FIBER-FORMING POLYMER IN A LIQUID WHICH IS A NONSOLVENT FOR THE POLYMER AND MAINTAINED AT A TEMPERATURE BELOW THE CRITICAL DRAFT 